Copending application Ser. No. 47,016, filed June 11, 1979, discloses a shelf structure and method for cooking two food products at different rates in a microwave oven. The shelf structure is placed on the rotating platform of a turntable in the oven cavity, and food products placed on the shelf cook at a different rate than food products placed directly on the turntable platform because of differences in the distribution of microwave energy at different heights in the cavity. While this shelf structure provides significant advantages in the simultaneous cooking of more than one food product in a microwave oven, it has certain limitations in that the shelf platform is always at a single fixed height and the structure which supports the platform can limit the size of food products which can be placed on the turntable platform when the shelf structure is in use.